The present invention relates to a process for the fabrication of contact structures in solar cells as well as solar cells having such contact structures. The present invention relates, in particular, to structures of grooves or holes and a process for their realization, which permits novel contacting of solar cells.
Solar cells are components which convert light into electric energy. Usually they are made of semiconductor material containing regions respectively layers of varying mobility for positive and negative charge carriers, n-type conductivity respectively p-type conductivity regions.
These regions are referred to as the emitter respectively as the base. The positive and negative charge carriers generated by incident light are separated and can be carried away by the metal contacts provided on the respective regions. Only those charge carriers contribute to the usual electric power of the solar cells which reach the contacts and which do not recombine with a respective other charge carrier.
The metal contacts are usually fabricated by means of vapor depositing metal, which is subsequently thickened by means of electroplating, by precipitating nickel without current or by pressing a metal paste onto the surface of the to-be-contacted regions. If these regions do not cover the entire solar cell surface or the metal can, for other reasons, only be deposited at certain points (e.g. shading of the light, increased recombination at the contact, etc.), as shall be described below, this is ensured by employing masks during fabrication.